1. Field of Industrial Use
This invention relates to a semiconductor laser device to be suitably used for a telecommunications or optical application as it is driven with an enhanced energy output level.
2. Prior Art
There has been an increasing demand for GaAs-type semiconductor laser devices capable of being driven with a high energy output level for telecommunications and optical applications.
When a semiconductor laser device is driven to show a high-output power level, there arise problems including catastrophic optical damage at the facets of laser and corrosion, when the device is used continuously for a long period of time.
It is believed that these problems take place when the temperature of the facets of a semiconductor laser device is subjected to a repetition of the cycle of rise in the surface temperature, reduction in the band gap, light absorption and increase in the surface recombination current.
A proposed solution for these problems is the provision of a structure (window structure) that effectively prevents the phenomenon of light absorption from occurring on the facets of a semiconductor laser.
More specifically, such a structure comprises part of an active layer that can effectively expand a band gap and hence suppress light absorption and optical damage of the part of the semiconductor laser device caused by light absorption.